In order to analyze various process steps in the fabrication of semiconductor devices, a method for identifying each semiconductor wafer is usually required. Conventionally, identification indications such as letters, numerals, or bar cords are written on each of the semiconductor wafers. The identification indication provides a method to identify each wafer after process conditions are applied to each of the wafers. By having an identification indication on each wafer the results of exposing the wafers to the conditions can be analyzed. This analysis of the effects of process conditions on wafers makes failure analysis and process feedback feasible, thus reducing the time for developing products and preventing errors from being repeated.
Generally, the identification indication is carved on top of the semiconductor substrate using a laser beam.
FIG. 1 is a diagram of a top plane view of a semiconductor wafer having an identification indication in accordance with the prior art. FIG. 2 is a diagram of a perspective view of a marking region illustrated in FIG. 1. FIG. 3 is a vertical cross-sectional view diagram taken along a line I-I′ of FIG. 2, which shows dots that are formed by laser marking.
Referring to FIGS. 1, 2, and 3, a marking region 20 is disposed at an edge 15 of an upper side of a semiconductor wafer 10. The marking region 20 is where an identification indication is written. Therefore, the usable chip region 25, in which semiconductor devices are formed, is decreased by as much area as is needed for the marking region 20. If the area of the chip region 25 decreases, then fewer chips can be produced per wafer, which leads to an increase in the unit cost of the semiconductor production.
In addition, the identification indication is composed of dots 30 that are conventionally formed by laser beam. As illustrated in FIG. 3, the dots 30 do not have flat shapes. This potentially can cause problems during the subsequent process of forming the semiconductor circuits on the wafer such as particle defects due to the non-uniform shape of the identification indication. In addition, the non-flat shapes of the dots 30 may cause a chuck defect while the semiconductor wafer 10 is being fixed.